The Design of an Optics-Based Bone Quality Sensing Device

Abstract

Treatment methods for spinal disorders involving spinal fusion surgery often entail lengthy and expensive procedures, with a risk of damage to surrounding tissues. Breach detection tools aid in precise pedicle screw placement, thereby reducing the risk of complications or misalignment, and minimizing the need for follow-up surgeries. Accurate placement of pedicles in the vertebrae is crucial in spinal fusion surgery, as improper positioning can result in breaches that potentially harm neural tissues. This study proposes a handheld bone sensing device capable of measuring real-time reflected light from tissue using carefully selected optical elements. The selection of these optical elements was guided by analyzing porcine absorption spectra and conducting Monte Carlo light reflectance simulations. The device is designed to provide consistent real-time feedback by incorporating an electronic circuit optimized to minimize environmental signal interference. A prototype, named the optics-based bone quality sensing device, was developed using electrical discharge machining parts, 3D printed parts, an Arduino Uno, a custom-made printed circuit board (PCB), and off-the-shelf optical components such as laser and photodiodes coupled into optical fibers. Experimental validation with ex vivo porcine vertebrae revealed that the device could not detect sufficient reflected light to differentiate between cortical and cancellous bone. Despite this, the study marks significant progress in creating a handheld bone sensing device that utilizes real-time reflected light sensing minimizing interference. This device represents an important step towards developing tools to assist in precise pedicle screw placement for the treatment of spinal disorders.